This invention relates to indexable cutting inserts of the type which are used, for example, in milling and boring cutters and in turning tools. An indexable cutting insert comprises a wafer made of cutting material such as tungsten carbide and usually having the shape of an equilateral polygon, there being a cutting edge along each side of the polygon. The insert seats within a locating pocket in the tool body and is held in the pocket by a locking pin which extends through a central hole in the insert. When one cutting edge becomes worn, the insert is turned or indexed in the pocket to bring a new cutting edge into active cutting position. After all of the cutting edges have been used, the insert usually is thrown away although, in some instances, the inserts are reground in order to renew the cutting edges.
Certain industrial dimensional standards have been established for indexable cutting inserts. For example, an insert which is shaped as a 0.75 inch square has a central pin-receiving hole with a diameter of about 0.312 inches. An insert which is shaped as a 0.625 inch square has a central hole with a diameter of about 0.250 inches. The latter insert thus uses a smaller diameter locking pin than the former insert.